The ethmoidal cells are part of the ethmoid bone, which is located in the inner part of the frontal, nasal and eye cavities. In addition to their stability function, they connect to nerves and are involved in olfactory perception. Fractures, nerve damage, tumors, inflammation as well as polyp formation can be possible diseases related to the ethmoid cells.
What are ethmoidal cells?
Ethmoidal cells (cellulae ethmoidale) belong to the ethmoid bone (Os ethmoidale), which is a bony area in the skull and the eye and nasal cavities. The naming borrows from the sieve-like structure of the holey bone. They are not “cells” in the medical-biological sense, but refer to the air-filled cavities. The entirety of the ethmoidal cells is also called the ethmoidal labyrinth (labyrinthus ethmoidalis).
Anatomy and structure
The ethmoid bone is anatomically located in an area that projects into and bounds both the frontal sinus and the nasal and orbital cavities. As a bony ramification, the ethmoid cells are penetrated by chambers, or cavities (pneumatization spaces). The ethmoid bones are thin-walled and have relatively large holes. Adjacent to the frontal sinus are about eight to ten ethmoidal cells. The ethmoidal cells are innervated in a broader sense via branches of the fifth cranial nerve (trigeminal nerve). On the one hand, nerve cords extend into the orbit via the posterior ethmoidal cells, where they connect to the paired optic nerve (nervus opticus). On the other hand, nerve cords from the anterior ethmoid cells extend into the nasal cavity (nasociliary nerve) via the ethmoid plate (lamina cribrosa). The lamina cribrosa is one of a total of four different bone plates (laminae) of the ethmoid bone. The pneumatization spaces of the paranasal sinuses are lined with mucosa and ciliated epithelium. In the nasal passage, the corresponding nerves supply the nasal mucosa through the ethmoid cells.
Function and tasks
The ethmoid bone as a whole is responsible for stability between the regions involved (skull base, orbit, nasal cavities). At the same time, it divides the areas, such as the base of the skull from the nasal cavity. Or the middle ethmoid bone, which together with the ploughshare bone (vomer) forms the nasal septum. It separates the anatomical structures. Directly related to the ethmoid cells is the olfactory system. It is through the olfactory nerves, which are connected to the olfactory bulb (bulbus olfactorius) and the nasal cavity via the cavities of the ethmoid plate, that our sense of smell comes about. The cavities in the ethmoid plate make it possible for the nerves to pass through and thus for olfactory perception to occur. Once the odor is detected via the nose, or more precisely via the olfactory receptor cells on the nasal mucosa, the stimulus is transmitted via the olfactory bulb to the cerebral cortex. Via the branched connection with the fifth cranial nerve, ophthalmic nerve (nervus ophtalmicus) and nerve branches of the upper jaw (nervus maxillaris) and lower jaw (nervus mandibularis) are involved, which is responsible, among other things, for the chewing movement. Thus, ethmoidal cells play an important role in stimulus transmission.
Diseases
Diseases affecting the ethmoid cells can be caused, on the one hand, by anatomical malformations that can result in chronic diseases. Similarly, the ethmoid cells can be affected by fractures of the bone plates, diseases of the nerve structures, and infections and ailments caused by bacteria and viruses. It should not be forgotten that allergic reactions can also be triggers for inflammation. Since the ethmoid bone is located in a sensitive area accessible through various pathways, the regions involved are particularly susceptible to disease. The best known disease is inflammation of the paranasal sinuses (sinusitis). A distinction is made between acute and chronic sinusitis. The ethmoid cells are part of the paranasal sinuses. Viruses, bacteria or allergies inflame the mucous membrane of the sinuses and promote swelling. As a further consequence, suppuration may occur. If pus is encapsulated in a cavity, this is called empyema. The sinuses also include the maxillary sinus, the sphenoid sinus and the frontal sinus. As the inflammation progresses, these regions may be affected. The disease of all parts of the paranasal sinuses is called pansinusitis.Antibiotics, local or oral cortisone preparations, special nasal rinses are used for sinusitis treatment. If the disease is so advanced that no improvement is achieved by medication, surgical intervention may be indicated. Also in case of polyp formation (proliferation of tissue), removal of ethmoid cells (ethmoidectomy) or partial surgical sanitation (removal of proliferated mucosa, polyps) is indicated. Inflammatory processes that spread via the eye, frontal sinus to the brain become dangerous. A bacterial infection of the frontal sinus can lead to meningitis. Early diagnosis of symptoms can prevent such ascending inflammation. Anatomical malformations can also promote chronic inflammation. Fractures or injuries at the base of the skull and the ethmoid plates increase the risk of cerebrospinal fluid (CSF) leakage. Inflammation can occur in the maxillary sinus area. Tooth root inflammation or purulent abscesses are often the cause of further diseases of the maxillary and paranasal sinuses. The connecting path between the upper jaw and the cranial nerve runs through the maxillary nerve. Diseases of the ethmoid nerve conduits include neuralgia, such as trigeminal neuralgia: a facial pain caused by the fifth cranial nerve (trigeminal nerve), often resulting from sinusitis. Diseases associated with the ethmoid cells further include tumors and cyst formations that interfere with nasal breathing and the natural drainage of secretions. Ethmoidal cells belong to a complex structure in which the eyes, brain, smell, chewing, breathing are indirectly involved, and diseases related to them can be just as far-reaching.
